How Does Palladium Coordination Affect the Electrophilicities of Allyl Cations? Development of a Robust Kinetic Method for Following Reactions of [(η<sup>3</sup>-Diarylallyl)Pd(PPh<sub>3</sub>)<sub>2</sub>]<sup>+</sup> with Nucleophiles
作者:Konstantin Troshin、Peter Mayer、Herbert Mayr
DOI:10.1021/om3000357
日期:2012.3.26
and fumaronitrile. The second-order rate constants (k2) for the attack of nucleophiles at the allyl ligands were found to follow the correlation log k2 = sN(N + E), where sN and N are solvent-dependent nucleophile-specific parameters and E is an electrophilicity parameter (J. Am. Chem. Soc.2001, 123, 9500–9512). While the electrophilicities of the free 1,3-bis(3,5-difluorophenyl)allyl (E = 6.11) and the
的反应的动力学[(η 3 -1,3-diarylallyl)的Pd(PPh 3)2 ] +与负碳离子,烯胺,胺,和三苯基膦已经光度在二氯甲烷调查络合物,DMSO,乙腈和在20℃下的解决方案。发现胺在钯(PPh 3的取代基)和烯丙基配体上均发生反应,从而导致复杂且重现性差的动力学。当在痕量PPh 3和富马腈的存在下研究反应时,实现了对烯丙基配体的进攻的二级速率常数的极好的重现性。二阶速率常数(k 2)对亲核试剂在烯丙基配体上的攻击遵循以下相关对数k 2 = s N(N + E),其中s N和N为溶剂依赖性亲核试剂特异性参数,E为亲电参数(J.化学会会志。2001,123,9500-9512)。游离的1,3-双(3,5-二氟苯基)烯丙基(E = 6.11)和1,3-双(4-二甲基氨基苯基)烯丙基阳离子(E = -7.50)的亲电性相差超过13个数量级在数量级上,相应的Pd(PPh3)2配合物被发现是几乎不依赖于取代基的性质(的Ë